Note that both first and last can be any integer. If first > last the interval is empty and the empty string is returned.

Breaking

Breaking with magnitudes

val take_left : int -> string -> string

take_left n s are the first n bytes of s. This is s if n >= length s and "" if n <= 0.

val take_right : int -> string -> string

take_right n s are the last n bytes of s. This is s if n >= length s and "" if n <= 0.

val drop_left : int -> string -> string

drop_left n s is s without the first n bytes of s. This is "" if n >= length s and s if n <= 0.

val drop_right : int -> string -> string

drop_right n s is s without the last n bytes of s. This is "" if n >= length s and s if n <= 0.

val break_left : int -> string -> string * string

break_left n v is (take_left n v, drop_left n v).

val break_right : int -> string -> string * string

break_right n v is (drop_left n v, take_right n v).

Breaking with predicates

val keep_left : (char -> bool)-> string -> string

keep_left sat s are the first consecutive sat statisfying bytes of s.

val keep_right : (char -> bool)-> string -> string

keep_right sat s are the last consecutive sat satisfying bytes of s.

val lose_left : (char -> bool)-> string -> string

lose_left sat s is s without the first consecutive sat satisfying bytes of s.

val lose_right : (char -> bool)-> string -> string

lose_right sat s is s without the last consecutive sat satisfying bytes of s.

val span_left : (char -> bool)-> string -> string * string

span_left sat s is (keep_left sat s, lose_left sat s).

val span_right : (char -> bool)-> string -> string * string

span_right sat s is (lose_right sat s, keep_right sat s).

Breaking with separators

val cut_left : sep:string-> string ->(string * string) option

cut ~sep s is either the pair Some (l,r) of the two (possibly empty) substrings of s that are delimited by the first match of the separator character sep or None if sep can't be matched in s. Matching starts from the left of s.

The invariant l ^ sep ^ r = s holds.

raises Invalid_argument

if sep is the empty string.

val cut_right : sep:string-> string ->(string * string) option

cut_right ~sep s is like cut_left but matching starts on the right of s.

val cuts_left : ?⁠drop_empty:bool->sep:string-> string ->string list

cuts_left sep s is the list of all substrings of s that are delimited by matches of the non empty separator string sep. Empty substrings are omitted in the list if drop_empty is true (defaults to false).

Matching separators in s starts from the left of s (rev is false, default) or the end (rev is true). Once one is found, the separator is skipped and matching starts again, that is separator matches can't overlap. If there is no separator match in s, the list [s] is returned.

The following invariants hold:

concat ~sep (cuts ~drop_empty:false ~sep s) = s

cuts ~drop_empty:false ~sep s <> []

raises Invalid_argument

if sep is the empty string.

val cuts_right : ?⁠drop_empty:bool->sep:string-> string ->string list

cuts_right sep s is like cuts_left but matching starts on the right of s.

Uniqueness

unique ~exist n is n if exists n is false or r = strf
"%s~%d" n d with d the smallest integer in [1;1e9] such that exists r is false or an error if there is no such string.

Suggesting

val edit_distance : string -> string -> int

edit_distance s0 s1 is the number of single character edits (insertion, deletion, substitution) that are needed to change s0 into s1.

val suggest : ?⁠dist:int->string list-> string ->string list

suggest ~dist candidates s are the elements of candidates whose edit distance is the smallest to s and at most at a distance of dist of s (defaults to 2). If multiple results are returned the order of candidates is preserved.

(Un)escaping bytes

The following functions can only (un)escape a single byte. See also these functions to convert a string to printable US-ASCII characters.

char_len c is the length of the unescaped byte c in the escaped form. If 1 is returned then c is assumed to be unchanged use byte_replacer if that does not hold

set_char b i c sets an unescaped byte c to its escaped form at index i in b and returns the next writable index. set_char is called regardless if c needs to be escaped or not in the latter case you must write c (use byte_replacer if that is not the case). No bounds check need to be performed on i or the returned value.

For any b, c and i the invariant i + char_len c = set_char b i c must hold.

char_len_at s i is the length of an escaped byte at index i of s. If 1 is returned then the byte is assumed to be unchanged by the unescape, use byte_unreplace if that does not hold.

set_char b k s i sets at index k in b the unescaped byte read at index i in s and returns the next readable index in s. set_char is called regardless of wheter the byte at i must be unescaped or not in the latter case you must write s.i only (use byte_unreplacer if that is not the case). No bounds check need to be performed on k, i or the returned value.

For any b, s, k and i the invariant i + char_len_at s i
= set_char b k s i must hold.

Both char_len_at and set_char may raise Illegal_escape i if the given index i has an illegal or truncated escape. The unescaper turns this exception into Error i if that happens.